The Maudsley Reactive rat is a strain of Wistar inbred rat which shows "hyperemotionality", characterized by a high incidence of freezing and defecation in an open field. Dr. Cottingham is characterizing this strain behaviorally and biochemically. Maudsley Reactives bred in our vivarium showed the expected high levels of freezing and defecation in our open field videotracking apparatus, as compared to Maudsley Non-Reactive and Sprague-Dawley controls. However, the Reactives showed no differences on the learned helplessness syndrome, or on t-maze memory paradigms. No differences between MNR and MR strains were found in mRNA for TH in adrenal gland or locus coeruleus, in mRNA for GAD in cortex, hippocampus, cerebellum, or striatum, or in mRNA for the gamma subunit of the GABA-A receptor in cortex or hippocampus. The MR had a significantly suppressed immune function, as measured by markers for t-cell and beta-cell proliferation.